Back to EveryPatent.com
United States Patent | 5,510,922 |
Naito | April 23, 1996 |
An optical frequency stabilizer comprises a signal light source for outputting signal light of a frequency f.sub.s ; a frequency shifter having a pumping light source to emit pumping light of a frequency f.sub.p and producing converted signal light of a frequency 2f.sub.p -f.sub.s from the signal light supplied thereto; a frequency discriminator for converting a frequency change of the received converted signal light into an intensity change; an optical detector for producing a detection signal in response to the output light of the frequency discriminator; an oscillator for outputting a low-frequency signal; a modulator circuit for frequency-modulating the signal light source in accordance with the low-frequency signal; a synchronous detector circuit connected operatively to the oscillator and the optical detector; an inverter circuit for inverting the output characteristic of the synchronous detector circuit; and a control circuit for controlling the signal light source in such a manner as to maintain constant the output level of the synchronous detector circuit. This optical frequency stabilizer has high frequency stability.
Inventors: | Naito; Takao (Kawasaki, JP) |
Assignee: | Fujitsu Limited (Kawasaki, JP) |
Appl. No.: | 458678 |
Filed: | June 2, 1995 |
Jun 28, 1994[JP] | 6-146186 |
Current U.S. Class: | 398/95; 372/24; 372/32; 398/93; 398/196 |
Intern'l Class: | H04J 014/02 |
Field of Search: | 359/124,134,158,160-162,182,187 372/24,32 |
5068864 | Nov., 1991 | Javan | 372/32. |
Foreign Patent Documents | |||
0521514 | Jan., 1993 | EP | 359/124. |
2-293826 | Dec., 1990 | JP. | |
0021936 | Jan., 1991 | JP | 359/124. |
5347606 | Dec., 1993 | JP | 359/124. |